[rollei_list] Re: Scanners
- From: Hauke Fath <hauke@xxxxxxxxxxxxxxxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Thu, 26 Nov 2009 21:54:10 +0100
At 12:16 Uhr -0800 26.11.2009, Richard Knoppow wrote:
> I am puzzled, I thought TIFF was compressed using
>non-lossy compression so that the original data could be
>recovered without change (unlike JPEG) and RAW was, as the
>name implies, the data coming from the camera or scanner in
>completely uncompressed form. Is this wrong?
Yes. TIFF stands for Tagged Image File Format; it is a so-called container
format (like Adobe PDF, these days), meaning you can put just about
anything into the file as long as a tag is defined for it. Programs reading
TIFF are not required to understand all possible formats. I think you can
have lossy as well as lossless compression of various kinds in TIFF, and of
course also non-compressed data.
I have to admit I am kind of mildly confused about the raw vs. RAW
discussion. My understanding is that RAW is a marketing term for
non-processed, non-interpolated or -colour-adjusted output from digital
cameras. Scanners have in the past always produced raw data, for lack of
built-in image processing capabilities. Today, raw scanner output would be
without ICE (VueScan can give you the IR channel in addition to the RGB
channels, so you can use that information in post-processing),
noise/sharpening filters, or lossy compression.
hauke
--
"It's never straight up and down" (DEVO)
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